How are different-sized photos handled?

Side-by-side matches every photo to the smallest height; stacked matches the smallest width. Aspect ratios are preserved and nothing is upscaled.

Can I control the order?

Yes — reorder with the arrows in the file list; the preview updates live.

No — stitching happens on a canvas in your browser.

Stitch photos side by side or stacked with automatic size matching, reordering and gap control — nothing upscaled, nothing uploaded.